Use binary decision approach to calculate SIT/NAT/SSA segments
it has some benefits when the partition size >= 512G.
(bsearch)
psize main_segments main_seaments
...
512G 261509 261510
1 T 523141 523143
2 T 1046405 1046409
4 T 2092783 2092791
...
It also clarify that SIT/NAT/SSA are used for main segment area only.
Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
---
Change log from v2:
- tighten binary search boundary (the lower bound is not as tight as the original one,
but very close and no more redundant code by this way.)
- some tests for this patch:
1) both can mkfs at the minimum partition size 38M and main segments are 11.
2) total binary search count optimize:
v2 v3 main_segments_count
512M 8 2 248
1G 9 3 502
2G 8 3 1011
4G 10 4 2029
8G 11 4 4065
16G 10 4 8135
32G 12 5 16275
64G 14 7 32581
128G 15 7 65285
256G 16 8 130693
512G 18 8 261510
1024G 16 10 523143
2048G 19 11 1026409
Change log from v1:
- use align_down instead of align_up in get_best_main_zones
mkfs/f2fs_format.c | 119 ++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 86 insertions(+), 33 deletions(-)
diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
index a130001..b9cae3a 100644
--- a/mkfs/f2fs_format.c
+++ b/mkfs/f2fs_format.c
@@ -145,20 +145,86 @@ static void verify_cur_segs(void)
c.cur_seg[i] = next_zone(i - 1);
}
+static u_int32_t get_meta_zones(u_int32_t main_zones)
+{
+ u_int32_t main_segments, meta_segments;
+ u_int32_t sit_segments, blocks_for_nat;
+ u_int32_t max_sit_bitmap_size, max_nat_bitmap_size;
+ u_int32_t nat_segments, ssa_segments;
+
+ main_segments = c.segs_per_zone * main_zones;
+
+ sit_segments = SEG_ALIGN(SIZE_ALIGN(main_segments,
+ SIT_ENTRY_PER_BLOCK) /* blocks_for_sit */);
+
+ blocks_for_nat = SIZE_ALIGN(main_segments * c.blks_per_seg,
+ NAT_ENTRY_PER_BLOCK);
+
+ max_sit_bitmap_size = min((u_int32_t)MAX_SIT_BITMAP_SIZE,
+ sit_segments * c.blks_per_seg / 8);
+
+ /*
+ * it's weird because for 1TB storage, payload is still not
+ * used and max_nat_bitmap_blks is only 21472, which means
+ * the total number of nodes is 21472 * 409 = 8782048
+ */
+ if (max_sit_bitmap_size > MAX_SIT_BITMAP_SIZE_IN_CKPT)
+ max_nat_bitmap_size = CHECKSUM_OFFSET -
+ sizeof(struct f2fs_checkpoint) + 1;
+ else
+ max_nat_bitmap_size =
+ CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1
+ - max_sit_bitmap_size;
+
+ nat_segments = min(SEG_ALIGN(blocks_for_nat),
+ (max_nat_bitmap_size * 8) / c.blks_per_seg);
+
+ /* each main segment has a ssa block */
+ ssa_segments = SEG_ALIGN(main_segments);
+
+ meta_segments = (get_sb(segment_count_ckpt) +
+ sit_segments * 2 + nat_segments * 2 +
+ ssa_segments);
+
+ return ZONE_ALIGN(meta_segments * c.blks_per_seg);
+}
+
+static u_int32_t get_best_main_zones(void)
+{
+ u_int32_t total_zones = get_sb(segment_count) / (c.segs_per_zone);
+ u_int32_t left = total_zones - get_meta_zones(total_zones),
+ right = total_zones - /* 2(CP + SIT + NAT) + SSA */
+ ZONE_ALIGN(7);
+ u_int32_t candicate = 0;
+
+ while (left <= right) {
+ u_int32_t main_zones = left + (right - left) / 2;
+ u_int32_t meta_zones = get_meta_zones(main_zones);
+
+ if (meta_zones + main_zones == total_zones)
+ return main_zones;
+
+ if (meta_zones + main_zones < total_zones) {
+ left = main_zones + 1;
+ candicate = main_zones;
+ } else
+ right = main_zones - 1;
+ }
+ return candicate;
+}
+
static int f2fs_prepare_super_block(void)
{
u_int32_t blk_size_bytes;
u_int32_t log_sectorsize, log_sectors_per_block;
u_int32_t log_blocksize, log_blks_per_seg;
u_int32_t segment_size_bytes, zone_size_bytes;
- u_int32_t sit_segments;
- u_int32_t blocks_for_sit, blocks_for_nat, blocks_for_ssa;
- u_int32_t total_valid_blks_available;
+ u_int32_t blocks_for_sit, blocks_for_nat;
u_int64_t zone_align_start_offset, diff;
u_int64_t total_meta_zones, total_meta_segments;
u_int32_t sit_bitmap_size, max_sit_bitmap_size;
u_int32_t max_nat_bitmap_size, max_nat_segments;
- u_int32_t total_zones;
+ u_int32_t main_zones, main_segments;
u_int32_t next_ino;
enum quota_type qtype;
int i;
@@ -256,22 +322,18 @@ static int f2fs_prepare_super_block(void)
set_sb(sit_blkaddr, get_sb(segment0_blkaddr) +
get_sb(segment_count_ckpt) * c.blks_per_seg);
- blocks_for_sit = SIZE_ALIGN(get_sb(segment_count), SIT_ENTRY_PER_BLOCK);
+ /* try to do binary decision to get main_zones */
+ main_zones = get_best_main_zones();
+ main_segments = c.segs_per_zone * main_zones;
- sit_segments = SEG_ALIGN(blocks_for_sit);
-
- set_sb(segment_count_sit, sit_segments * 2);
+ blocks_for_sit = SIZE_ALIGN(main_segments, SIT_ENTRY_PER_BLOCK);
+ set_sb(segment_count_sit, SEG_ALIGN(blocks_for_sit) * 2);
set_sb(nat_blkaddr, get_sb(sit_blkaddr) + get_sb(segment_count_sit) *
c.blks_per_seg);
- total_valid_blks_available = (get_sb(segment_count) -
- (get_sb(segment_count_ckpt) +
- get_sb(segment_count_sit))) * c.blks_per_seg;
-
- blocks_for_nat = SIZE_ALIGN(total_valid_blks_available,
+ blocks_for_nat = SIZE_ALIGN(main_segments * c.blks_per_seg,
NAT_ENTRY_PER_BLOCK);
-
set_sb(segment_count_nat, SEG_ALIGN(blocks_for_nat));
/*
* The number of node segments should not be exceeded a "Threshold".
@@ -312,16 +374,7 @@ static int f2fs_prepare_super_block(void)
set_sb(ssa_blkaddr, get_sb(nat_blkaddr) + get_sb(segment_count_nat) *
c.blks_per_seg);
- total_valid_blks_available = (get_sb(segment_count) -
- (get_sb(segment_count_ckpt) +
- get_sb(segment_count_sit) +
- get_sb(segment_count_nat))) *
- c.blks_per_seg;
-
- blocks_for_ssa = total_valid_blks_available /
- c.blks_per_seg + 1;
-
- set_sb(segment_count_ssa, SEG_ALIGN(blocks_for_ssa));
+ set_sb(segment_count_ssa, SEG_ALIGN(main_segments));
total_meta_segments = get_sb(segment_count_ckpt) +
get_sb(segment_count_sit) +
@@ -354,10 +407,7 @@ static int f2fs_prepare_super_block(void)
}
}
- total_zones = get_sb(segment_count) / (c.segs_per_zone) -
- total_meta_zones;
-
- set_sb(section_count, total_zones * c.secs_per_zone);
+ set_sb(section_count, main_zones * c.secs_per_zone);
set_sb(segment_count_main, get_sb(section_count) * c.segs_per_sec);
@@ -373,6 +423,9 @@ static int f2fs_prepare_super_block(void)
return -1;
}
+ ASSERT((total_meta_zones + main_zones) * c.segs_per_zone
+ == get_sb(segment_count));
+
c.reserved_segments =
(2 * (100 / c.overprovision + 1) + 6)
* c.segs_per_sec;
@@ -404,15 +457,15 @@ static int f2fs_prepare_super_block(void)
qtype, next_ino - 1);
}
- if (total_zones <= 6) {
+ if (main_zones <= 6) {
MSG(1, "\tError: %d zones: Need more zones "
- "by shrinking zone size\n", total_zones);
+ "by shrinking zone size\n", main_zones);
return -1;
}
if (c.heap) {
c.cur_seg[CURSEG_HOT_NODE] =
- last_section(last_zone(total_zones));
+ last_section(last_zone(main_zones));
c.cur_seg[CURSEG_WARM_NODE] = prev_zone(CURSEG_HOT_NODE);
c.cur_seg[CURSEG_COLD_NODE] = prev_zone(CURSEG_WARM_NODE);
c.cur_seg[CURSEG_HOT_DATA] = prev_zone(CURSEG_COLD_NODE);
@@ -424,10 +477,10 @@ static int f2fs_prepare_super_block(void)
c.cur_seg[CURSEG_COLD_NODE] = next_zone(CURSEG_WARM_NODE);
c.cur_seg[CURSEG_HOT_DATA] = next_zone(CURSEG_COLD_NODE);
c.cur_seg[CURSEG_COLD_DATA] =
- max(last_zone((total_zones >> 2)),
+ max(last_zone((main_zones >> 2)),
next_zone(CURSEG_COLD_NODE));
c.cur_seg[CURSEG_WARM_DATA] =
- max(last_zone((total_zones >> 1)),
+ max(last_zone((main_zones >> 1)),
next_zone(CURSEG_COLD_DATA));
}
--
2.1.4
